Fix STL for 3D Printing

I have an existing STL that won’t slice cleanly and needs professional repair before it goes near the printer. Your task is to hunt down and eliminate every geometry issue—non-manifold edges, stray vertices,... (Budget: $14 - $80 NZD, Jobs: 3D Animation, 3D CAD, 3D File Scaling, Slicing & Print Preparation, 3D Modelling, 3D Printing, 3D Rendering, Blender, Solidworks)